巻号一覧
52 巻, 6 号
選択された号の論文の7件中1～7を表示しています
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研究論文
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隠岐 貴史, 松木 一弘, 清水 功史, 柳沢 平2002 年 52 巻 6 号 p. 243-249
発行日: 2002年
公開日: 2007/03/30
ジャーナル フリーThe composites of the different dispersion state were prepared from the titanium powder and the TiC with the different particle sizes. The effect of the difference of spatial distribution of the TiC particles on the tensile properties and the behavior of TiC particles' breaking in the tensile deformation process have been quantitatively investigated. In tensile deformation, TiC particles begin to break just after the yielding of the material. Finally the connection of cumulated cracks of particles brings the propagation of a main crack and fracture of the composite material. The material of which the spatial distribution of the second phase particles is close to random distribution has larger tensile strength and tensile ductility than the material of stronger clustering tendency. The reason for this is that the destruction of TiC particles in the materials of stronger clustering tendency is more frequent from the initial stage of the deformation, because they have more regions of larger local volume fraction and larger local particle density. The tendency, showing that the particles in the clustered regions are easy to be broken, was explained from the result of the elastic-plastic analysis by finite element method.抄録全体を表示PDF形式でダウンロード (552K) -
倉本 繁, 謝 明君, 菅野 幹宏2002 年 52 巻 6 号 p. 250-255
発行日: 2002年
公開日: 2007/03/30
ジャーナル フリーTwo medium-strength Al–Mg–Si alloys exhibited environmental embrittlement when deformed in laboratory air at low strain rates. Tensile specimens prepared from hot rolled plates of Al–0.75%Mg–0.75%Si and Al–0.75%Mg–0.75%Si–0.35%Cu alloys were solution treated for 1 h at 540°C, quenched in water and aged for 30 min at 175°C. They were deformed in tension at initial strain rates ranging from 1.7 × 10−7 to 8.3 × 10−4 s−1 in a laboratory air with a relative humidity of 40–80%. Both alloys showed ductile transgranular fracture when tested at a strain rate of 8.3 × 10−4 s−1, however, they exhibited intergranular embrittlement with lower tensile elongation and reduction in area when tested at a strain rate of 1.7× 10−7 s−1. This tendency of intergranular embrittlement is prominent in the Al–0.75%Mg–0.75%Si–0.35%Cu alloy and the effect of hydrogen absorbed from the test environment on such embrittlement was studied using deuterium as a tracer of hydrogen.抄録全体を表示PDF形式でダウンロード (662K) -
久富 裕二, 正路 美房2002 年 52 巻 6 号 p. 256-261
発行日: 2002年
公開日: 2007/03/30
ジャーナル フリーThe brazing behavior of aluminum clad fin with thickness from 60 to 80 μm for automotive heat exchangers was studied in order to improve the fillet forming ability which usually declines with reduction of fin thickness. Three types of core alloys (Al–1.2 mass%Mn–0.06~0.57 mass%Si–1.5 mass%Zn) and four types of filler metals (Al–7.35~9.50 mass%Si) were used. The fillet area, formed on the fin and tube joints, increased with increasing the silicon content of both core alloys and filler metals. The result was caused by the diffusion of silicon from the filler into the core alloy during the heating processes of intermediate annealing and brazing. Consequently, the reduction of silicon concentration in filler metal became small with the increase in the silicon content of core alloy. The flow factor decreased with decreasing the fin thickness due to the residual filler with constant quantity on the surface of clad fin. The fillet area tended to increase in proportion to the average concentration of silicon in clad fin. Then, the fillet was not formed at the low silicon concentration, whereas the fin deformed due to the erosion of core alloy contacting with molten filler metal at the high silicon concentration.抄録全体を表示PDF形式でダウンロード (527K) -
横山 隆2002 年 52 巻 6 号 p. 262-268
発行日: 2002年
公開日: 2007/03/30
ジャーナル フリーHigh strain-rate tensile stress-strain characteristics of AC4CH–T6 aluminum casting alloys are evaluated using the split Hopkinson bar. Tensile stress-strain data up to fracture are determined at strain rates of 500–800/s and compared with those at quasistatic and medium strain rates obtained on an tensile testing machine. The effect of strain rate on the tensile strength, elongation at fracture and absorbed Instron is investigated. It is shown that the tensile strength increases slightly, whereas the elongation at fracture and the absorbed energy decrease considerably with increasing strain rate. Microscopic examination reveals almost no difference between the static and impact fracture surface morphology of tension specimens. The large variation of the tensile properties is primarily attributed to the presence of microshrinkage defects within the aluminum casting alloy.抄録全体を表示PDF形式でダウンロード (567K) -
多田 清志, 小堀 一博, 植木 光彦2002 年 52 巻 6 号 p. 269-275
発行日: 2002年
公開日: 2007/03/30
ジャーナル フリーWe investigated the corrosion mechanism of the aluminum condenser on the basis of electrochemical measurement for automotive air conditioning system in actual use environment where large amounts of antifreezing admixture were sprayed in winter. It was concluded that corrosion occurred in the following two steps: At the first step, repetition of adhesion and drying of the salt water caused to form a chloride ion concentration cell in the water droplet and then corrosion started on the surface of the condenser tubes. At the second step, the pits with the aspect ratio (= depth of pit/surface diameter of pit) larger than 1, which was generated in the first step, proceeded further and pH decreased by concentrating hydrochloric acid content at the bottom of the pits, leading to the growth of the pits.抄録全体を表示PDF形式でダウンロード (616K) -
本堂 和明, 菅又 信, 金子 純一, 久保田 正広2002 年 52 巻 6 号 p. 276-281
発行日: 2002年
公開日: 2007/03/30
ジャーナル フリーWith a purpose of obtaining materials showing high specific strength at room temperature and superplastic elongation at elevated temperatures, Mg–8Ag (mass%) alloys with various ternary alloying additions were rapidly solidified by gas atomizing and subsequent splat quenching. The rapidly solidified flakes were consolidated to the P/M materials by hot extrusion at 573 K. The structures and mechanical properties were examined for as-rapidly solidified flakes, as-extruded P/M materials before and after heating at various temperatures. The obtained P/M materials showed fine and uniform dispersion of the second phase particles. At room temperature, the highest tensile strength of 580 MPa was obtained for rapidly solidified Mg–8Ag–8Ce alloy with elongation higher than 3%. This corresponds to a high specific strength of 290 MPa/g/cm3. The highest tensile strength of 334 MPa at 473 K was observed for Mg–8Ag–5Ca alloy. Tensile elongation increased with rising test temperature and superplastic elongation above 200% was observed at 573 K for Mg–8Ag–8Al, Mg–8Ag–8Zn and Mg–8Ag–5Ca alloys. The highest elongation above 300% was observed at 573 K for the as-extruded P/M materials of Mg–8Ag–8Al and Mg–8Ag–5Ca alloys at an initial strain rate of 1.7 × 10−2/s.抄録全体を表示PDF形式でダウンロード (487K)
解説
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藤原 雅美2002 年 52 巻 6 号 p. 282-290
発行日: 2002年
公開日: 2007/03/30
ジャーナル フリーPDF形式でダウンロード (525K)
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